It is observed in Nature that the embryonic developments of different kinds of species require different types of environments. It is assumed in this paper that there may exist some kind of imposed gradient or pre-assigned gradient, generated as a resultant effect of the environment, acting on the developing embryo. This system has been studied by constructing a suitable mathematical model of epigenetic mechanism. It has been observed that the introduction of this imposed gradient can easily change any existing pattern of the embryo. Model analysis has been performed using the Turing approach